Monomer compounds in which the carbon atoms forming a double bond are directly bonded to iodine atoms are known; however, there are few examples of monomer compounds in which an iodine atom is bonded to the end of the long side chain. The synthesis of such monomer compounds using a known method has a long synthesis route and results in a poor yield; thus, productivity is extremely low (see Patent Documents 1 and 2).
Moreover, the synthesis of terminally iodized fluorine-containing monomers generally requires multistep reactions, each reaction of which is very troublesome. On the other hand, many unsaturated compounds having a bromine atom at the end of the long side chain are known; however, terminal bromine atoms have less reactivity than terminal iodine atoms.